When Ms. Thelma turned on her oven, the temperature inside was 70 degrees F. The temperature began t

When Ms. Thelma turned on her oven, the temperature inside was 70 degrees F. The temperature began to rise at a rate of 20 degrees per minute. How Long did it take for the oven to reach 350 degrees F?

Figure out how many degrees we have left:
350 - 70 = 280

Let m = minutes
20m = 280

Divide each side by m
m = 14