Calculate areas for 2 rectangles;
21*9= 189
18*42= 756
make an equation with data you have;
If 189 cost $1.31
756 cost $x
_____________
756 *1.31 / 189 = $5.24 cost for second fabric
Second way;
(18x42) / (21x9) = 4 x 1.31 = $5.24
Which ever you find easer
