En un salón de clase, antes del recreo el número de hombres es al número de mujeres como 8 es a 7. Si después del recreo, hay 6 hombres y 9 mujeres menos, con lo cual la razón de hombres a mujeres es 5/4, hallar cuántas mujeres había antes del recreo.

  or  

step-by-step explanation:

if the four friends split the cost, p, of the pizza evenly, then each friend pays one-fourth of the cost of the pizza.

the expression is   or  

this is the formula: v = the value of investment at the end of the time period

p = the principal amount (the initial amount invested)

r = the annual interest rate

n = the annual frequency of compounding (how many times a year interest is added)

t = the number of years the money is invested

^ means raise to the power of