Bonjour,
a)
2 + (3,5 * x) = 23
2 + 3,5x = 23
3,5x = 23 -2
3,5x = 21
x= 21/3,5
x= 6
b)
Périmètre d'un rectangle:
2(L+l)
2( 12,5 +l ) = 36
25 + 2 l = 36
2 l = 36 - 25
2 l = 11
l = 11/2
l = 5,5 cm
c)
adultes = 80x
(50*125) + 80x = 11 850
6 250 + 80x = 11 850
80x = 11 850 - 6 250
80x = 5600
x= 5 600/ 80
x = 70
70 adultes