А) (-13+6)*t + (12-17)*q = -7*t - 5*q = - (7*t + 5*q)
б) -(2 1/8 + 7/36 + 1/2 - 3/4)*с
НОК(2,4,8,12,36) = 72
- ( 2 9/72 + 14/72 +36/72 - 18/72)*с = - 2 5/72
(2/3 + 7/12) = (8/12 + 7/12) = 15/12
16/25 * 15/12 = 4/5 * 3/3 = 4/5
9/10:15/16 = 9/10 * 16/15 = 144/150 = 72/75
4/5 - 72/75 = 60/75 - 72/75 = -12/75
-12/75 = -4/25 = -0.16
9000 ÷ 6 = 1500
9000|_6___
-6 | 1500
___
-30
30
___
0
48-18=30 мальчики
30/48=5/8 составляют мальчики.