Let t = number of hours
The first candle starts at 8 inches.
It burns at 7/10 inch per hour, so in t hours it burns (7/10)t inches.
After t hours, its length is 8 - (7/10)t
The second candle starts at 6 inches.
It burns at 1/5 inch per hour, so in t hours it burns (1/5)t inches.
After t hours, its length is 6 - (1/5)t
You want the lengths to be equal, so the equation is
8 - (7/10)t = 6 - (1/5)t
Do you know what you need to do to solve this problem?
Si tiene que divide 212/100=53/25
The answer would be 10! I divided the number of plants that you can water with 4 gallons (14) by, well, the number of gallons it takes to water them (4) and got 3.5 (14 / 4 = 3.5), the number of plants you can water with one gallon. I then divided the number of plants you need to water (35) by the number of gallons it takes to water one plant (3.5) and came up with 10. I hope this helps you!