Will mark brainliest !! Easy math

increase = 37.38 cm²

You'd like the first way because it took less effort and less chance of a miscalculation.

Step-by-step explanation:

first way:

(just work with the difference in height)

(0.7 x 8.7 x 2) + (0.7 x 18 x 2) = 37.38 cm²

second way:

old total lateral surface area = (31 x 8.7 x 2) + (31 x 18 x 2) = 1655.4

new total lateral surface area = (31.7 x 8.7 x 2) + (31.7 x 18 x 2) = 1692.78

increase = 1692.78 - 1655.4 = 37.38 cm²

answer: give more info

step-by-step explanation: