Need both equations solved with explanation.

Janets dinner costs 7.50. if she wants to leave a 10% tip how mich extra should she leave

Solve with work adding cheese to a mcdonalds quarter pounder increases the fat content from 21g to 30g. what is the percent of change ?

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6