Question

a-b=13 c+d=11 4c+4d-(3a-3b); 59-(2a-2b)-(3c+3d).

Answer 1

a-b=13
a=13+b
a=13+b
b €R

c+d=11
c=11-d
c=11
d €R



4c+4d-(3a-3b)

4c+4d-3a+3b



59-(2a-2b)-(3c+3d)
59-2a+2b-3c-3d

Answer 2

a-b=13 ;  c+d=11

4c+4d-(3a-3b) = 4·(c+d) -3·(a-b) = 4·11 -3·13 = 44-39 = 5

59-(2a-2b)-(3c+3d) = 59-2·(a-b)-3(c+d) = 59-2·13-3·11 = 59-26-33 = 0