Question

tinand cont ca x=3 afla a+3b stiind ca a xa+3xb=51 b 2a+6b-x=21 c 8x-a-3b=7 d 4a+12b=27-x e 5ax+15xb-2x=144

Answer 1

a) xa+3xb=51
   3(a+3b)=51
a+3b=51/3=17

b) 2a+6b-x=21
2(a+3b)-3=21
a+3b=24/2=12

c) 8x-a-3b=7
8*3-(a+3b)=7
a+3b=24-7=17

d) 4a+12b=27-x
4(a+3b)=27-3
a+3b=24/4=6

e) 5ax+15xb-2x=144
5x(a+3b)-2x=144
5*3*(a+3b)-2*3=144
15*(a+3b)-6=144
15*(a+3b)=144 +6
15*(a+3b)=150
a+3b=10