The temperature is -4°f. a high pressure front increases the temperature to 8°f. by how many degrees did the temperature increases?

The temperature had to rise 4 degrees to reach zero, and then another 8 degrees to reach 8.  The total increase was (4 + 8) = 12 degrees.

A more formal way to do it:

The change is (end value) minus (start value)

Change = (8) - (-4) = (8) + (4) = 12 degrees.

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.

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