Solve for 2 unknowns : 3a+4b=9; 2a+2b=6

Let us take the second equation first

2a + 2b = 6

Dividing both sides by 2 we get

a + b = 3

a = 3 - b

Putting the value of a in the first equation we get

3a + 4b = 9

3 (3 - b) + 4b = 9

9 - 3b + 4b = 9

b = 9 - 9

= 0

Now putting the value of b in the second equation we get

a + b = 3

a + 0 = 3

a = 3

So the value of the unknown variable a is 3 and the value of the unknown variable b is 0.