Both equations contain 2b, so rearrange:
10a-2b=30, 2b=10a-30; 3a-2b=2, 2b=3a-2.
The RHS of the two revised equations must be equal, so:
10a-30=3a-2,
7a=28, a=4.
2b=3a-2=10a-30, so 2b=3×4-2=10×4-30=10, b=5.
SOLUTION a=4, b=5.
The same result is obtained by subtracting the original equations:
10a-2b-(3a-2b)=30-2,
10a-2b-3a+2b=28,
7a=28, a=4.
3a-2b=2, 12-2b=2, 10=2b, 5=b, b=5.