Question

When 31 times a number is increased by 40, the answer is the same as when 200 is decreased by the number

Answer 1

n - a number

31 times a number is increased by 40 is equal 200 is decreased by the number

31n + 40 = 200 - n      subtract 40 from both sides

31n = 160 - n      add n to both sides

32n = 160     divide both sides by 32

n = 5

Answer 2

$31x+40=200-x\\32x=160\\x=160/32\\x=5$

The number is 5.