Sagot :

Bjr,

R = 5.8 * (50 - a) + 8.5 * a

R = 5.8 * 50 + 5.8 * - a + 8.5a

R = - 5.8a + 290 + 8.5a

R = 2.7a + 290

a = 35

R = 2.7 * 35 + 290 = 384.5 euros

pareil pour a = 42.