Remark
Supplementary angles add up to 180o.
Givens
<1 = 124
<2 = 2x + 4
I imagine you are looking for either x or <2.
Equation
<1 + <2 = 180 Substitute the givens
124 + 2x + 4 = 180 Collect like terms on the left.
128 + 2x = 180 Subtract 128 from both sides
2x = 180 - 128 Collect like terms on the right
2x = 52 divide by 2
x = 52/2
x = 26 <<<<<<<<< answer
<1 = 124
<2 = 2x + 4 = 2*26 + 4
<2 = 52 + 4
<2 = 56 <<<<<<<< answer
We need choices if you want an exact answer.