(a + b) + (a + c) + (a + d) + (b + c) + (b + d) + (c + d при a + b + c + d = 1,5помогите...

Question

(a + b) + (a + c) + (a + d) + (b + c) + (b + d) + (c + d при a + b + c + d = 1,5

помогите решить

Answer 1

3а+3b+3с+3d=3(a+b+c+d)=3*1,5=4,5