I know the answer but i just need the work

Emily is entering a bicycle race for charity. her mother pledges $0.90 for every 0.75 mile she bikes. if emily bikes 18 miles, how much will her mother donate?

If 7x=9y, y/z = 7/5 , then x/z = (a) 2/7 (b) 7/9 (c) 9/5 (d) 9/7 (e) 5/9

Last week jason walked 3 1/4 miles each day for 3 days and 4 5/8 miles each day for 4 days. about how many miles did jason walk last week?