This is a proportion. First you take the numerator times the denominator that is already solved. In this case you will take 5 times 7 and get 35. You then take 35 divided by 4 and get your answer.
X° + 123° + 90° = 360° (angles at a point)
x° = 360° - 90° -123°
x° = 147°
The answer of x is 147°
Hope I can help you :)
For one sweater it would be $10.88 but if she got 3 it would be $32.64
10.88•8=32.64