I don’t get this and I need help on this

19a. Let's let # of weeks equal x and amount of savings equal s.

50+7.5x = s

19b. With this equation we can find savings in 3 weeks by plugging in 3 for x

50+7.5(3) = s

Combine like terms.

72.5 = s

19c. We first multiply 6 x 4 to give us the number of weeks.

6 x 4=24

Next we plug it in the same way as in the last problem.

50+7.5(24)=s

Combine like terms.

230=s

19d. Now we need to plug in 275 for our savings like this:

50+7.5x=275

Subtract 50 from both sides of the equation.

7.5x=225

Divide both sides by 7.5 .

x=30

HTH :)