First, you find the area of RPQ using 1/2×base×height. That is, 1/2×6×8. And the answer is 24. Then you multiply 24 by 4 to get the area of all the sides excluding the base to get 96.
Notice how all of these get you the same number. However, when you divide 90 by 137, you get 0.64748, which is not the same as the others. Therefore, 90/137 is the fraction that is not equivalent to 45/70.
