Math CentralQuandaries & Queries


Question from Allen, a student:

Solve each literal equation for the indicated variable.

D= C-S/n (solve for s)


A=1/2h (B+b) (solve for b)

Hi Allen,

Let me try a similar problem.

The percentage increase in sales in my store this year over the lasles last year is given by

P = (T - L)/L × 100

where P is percentage increase, T is the sales this year in dollars and L is the sales this year in dollars. Solve for T.

I would start by multiplying both sides by L to eliminate the fraction, thus

P × L = (T - L) × 100 = 100 T - 100 L

Now add 100 L to both side to obtain

P × L + 100 L = 100 T


T = (P × L + 100 L)/100

You can make it look a little neater by taking out a common factor of L on the right side

T = L × (P + 100)/100

I hope this helps,

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