To solve this problem, we just need to set up a simple equation. We have that angles 1 and 2 add up to equal a right angle, or 90°, and that m<2 is 35°, so we just have to do a bit of subtraction.
<1 + <2 = 90 Given
<1 + 35 = 90 Substitute 35 for <2
<1 = 55° Subtract 35 from both sides to get rid of it, since subtraction is the opposite of addition.
Therefore, m<1 = 55°.
Hope this helps!