So… 29+30+31 = 90.

2nd problem:

supplement(S) plus the angle(A) = 180

so S = 20 + 3*A

and S + A = 180

Can you solve simultaneous equations?

Replace S in the 2nd equation with the first equation and solve for A.

Ok, here’s how you solve them.

We already know that S = 20 + 3*A

We plug that into the other equation:

S + A = 180

is the same as:

(20 + 3*A) + A = 180

So: 20 + 3*A + A = 180

20 + 4*A = 180

4*A = 160

So A = 40 degrees

Therefore S = 180 – 40 = 140 degrees.

So the original angle is 40 º and the supplement is 140 º .

I hope you understand how it was solved. Practice more simultaneous equations to get good at them. They’re not hard. Just isolate one variable and plug it into the other equation. Good luck with your studies.