Question

10a+2b=4, 15a-5b=2 substitute

Answer 1

10a+2b=4--------(1)
15a-5b=2----------(2)

multiplying equation number 1 by 5 and equation number 2 by 2
50a+10b=20-----(3)
30a-10b=4---------(4)

adding equation no. 3 and 4
80a=24
a=24/80
a=3/10

put a=3/10 in equation no. 1
10a+2b=4
10×3/10+2b=4
3+2b=4
2b=4-3
2b=1
b=1/2

(a,b)=(3/10,1/2)