Nadia charges $7.50 an hour for babysitting. she babysits 18.5 hours the first week of the month and 20 hours the second week of the month. to find her total earnings for those two weeks, nadia writes 7.5 x 18.5 = 20 = $158.75. explain her error. show the correct solution.

7.5× 18.5=138.75 first week
7.5×20=$150 second week
total earnings 138.75+150=$288.75
She did multiply correctly 7.5 ×18.5 but got the wrong figure resulting in in lower pay and she did not multiply the 7.5 × 20 in the seond week. She shouldve added the week one and two wages to get her pay for 2 weeks

Iknow one of the answers is a and maybe b but not 100% sure about b