no 38,39,sama 40 gimna caranya?

38. 7 = 15+6x+28+32+18/ 13+x
91+7x = 93 + 6x
7x-6x = 93-91
x = 2

39. (18+24)-30
42-30
12

P = 12/30 = 0,4

40. 4/8 x 3/7 = 12/56 = 3/14