28/21 = 42/x solve for x
a: 14
b: 18 2/3
c: 31 1/2
d: 56
i cant figure out what it is, and im slightly confused

Mary used 1/7 of a spool of ribbon to complete 4 projects. she used the same amount of ribbon on each project. how much ribbon did she use on each project?

2,10,-50 next two numbers geometric sequence

The water company charges a residential customer $41 for the first 3,000 gallons of water used and $1 for every 200 gallons used over 3000 gallons. if the water bill was $58 how many gallons of water were usedanswersa 3400 gallonsb 6000 gallonsc 6400 gallons d 7000 gallons