All, Anyone see what I am doing wrong here? \setupcolors[state=start] \definecolor[gridlines][s=0.7] \startMPinclusions color mygridcolor; mygridcolor=\MPcolor{gridlines}; \stopMPinclusions \starttext \startbuffer[one] % initialize scale numeric u; 10u=4cm; % draw grid for k=-5u step 1u until 5u: draw (-5u,k)--(5u,k) withcolor mygridcolor; draw (k,-5u)--(k,5u) withcolor mygridcolor; endfor; % draw axes drawdblarrow (-5.2u,0)--(5.2u,0); drawdblarrow (0,-5.2u)--(0,5.2u); % label axes label.rt(btex $\tfx x$ etex, (5.2u,0)); label.top(btex $\tfx y$ etex, (0,5.2.u)); label.bot(btex $\tfx 5$ etex, (5u,0)); label.lft(btex $\tfx 5$ etex, (0,5u)); %draw the given line and the parallel line drawdblarrow (-5u,-4.5u)--(5u,0.5u) withcolor blue; label.bot(btex $\tfx x-2y=4$ etex, (-5u,-4.5u)); %pairs pair Q, R; R:=(4u,0u); Q:=(0u,-2u); %labels dotlabel.lrt(btex $\tfx R(4,0)$ etex, R); dotlabel.lrt(btex $\tfx Q(0,-2)$ etex, Q); \stopbuffer \startbuffer[two] % initialize scale numeric u; 10u=4cm; % draw grid for k=-5u step 1u until 5u: draw (-5u,k)--(5u,k) withcolor mygridcolor; draw (k,-5u)--(k,5u) withcolor mygridcolor; endfor; % draw axes drawdblarrow (-5.2u,0)--(5.2u,0); drawdblarrow (0,-5.2u)--(0,5.2u); % label axes label.rt(btex $\tfx x$ etex, (5.2u,0)); label.top(btex $\tfx y$ etex, (0,5.2.u)); label.bot(btex $\tfx 5$ etex, (5u,0)); label.lft(btex $\tfx 5$ etex, (0,5u)); %draw the given line and the parallel line drawdblarrow (-5u,-4.5u)--(5u,0.5u) withcolor blue; label.bot(btex $\tfx x-2y=4$ etex, (-5u,-4.5u)); drawdblarrow (-4u,5u)--(1u,-5u) withcolor blue; %pairs pair P, Q, R; P:=(-3u,3u); Q:=(-3u,1u); R:=(-2u,1u); draw P--Q--R withpen pencircle scaled 1pt withcolor red; label.lft(btex $\tfx \Delta y=-2$ etex, 0.5[P,Q]); label.bot(btex $\tfx \Delta x=1$ etex, 0.5[Q,R]); %labels dotlabel.urt(btex $\tfx (-3,3)$ etex, P); \stopbuffer \startbuffer[combined] \startcombination[2*1] {\processMPbuffer[one]}{(a)} {\processMPbuffer[two]}{(b)} \stopcombination \stopbuffer \startlinecorrection[blank] \midaligned{\getbuffer[combined]} \stoplinecorrection %\startlinecorrection[blank] %\midaligned{\processMPbuffer[two]} %\stoplinecorrection \stoptext I am getting this error: ! Arithmetic overflow. <recently read> \@@raggedskipb \setraggedness ...e \@@raggedskipa \@@raggedskipb \hyphenpenalty \@@raggedsk... \raggedcenter ->\setraggedness \middleraggedness \setraggedskips 2 \middlerag... \@@align@@middle ...gedcenter \else \raggedcenter \fi \fi \next2 #1,->\dodosetupalign {#1} \doprocesscommaitem \doprocesscommalist ...item \gobbleoneargument #1, ]\relax \global \advance \... ... l.3 {\processMPbuffer[two]}{( b)} ? It doesn't seem to be the Metapost code, because if you uncomment and comment the last few lines like this: %\startbuffer[combined] % \startcombination[2*1] % {\processMPbuffer[one]}{(a)} % {\processMPbuffer[two]}{(b)} % \stopcombination %\stopbuffer % %\startlinecorrection[blank] %\midaligned{\getbuffer[combined]} %\stoplinecorrection \startlinecorrection[blank] \midaligned{\processMPbuffer[two]} \stoplinecorrection It compiles fine. So does this: I'm stymied.