Let the number of large frames be x Let the number of small frames be y Cost Cost Type Number of of of of EACH ALL frame frames frame frames ------------------------------------------- large x $11 $11x small y $7 $7y ------------------------------------------- TOTALS 26 ----- $218 The first equation comes from the "number of frames" column.x + y = 26 The second equation comes from the last column. 11x + 7y = 218 So we have the system of equations: . We solve by substitution. Solve the first equation for y: x + y = 26 y = 26 - x Substitute (26 - x) for y in 11x + 7y = 218 11x + 7(26 - x) = 218 11x + 182 - 7x = 218 4x + 182 = 218 4x = 36 x = 9 = the number of large frames. Substitute in y = 26 - x y = 26 - (9) y = 17 small frames. Checking: 9 large frames cost $99 and 17 small frames is $119 That's 26 frames. And indeed $99 + $119 = $218 Edwin