The weather forecast predicted that the evening temperature could get as low as -12.5 Fahrenheit. Between the afternoon and evening the temperature dropped by 7.5 Fahrenheit, and the forecast was still correct. What could the afternoon temperature tea have been?

-5

Step-by-step explanation:

t – 7.5 ≥ −12.5

t − 7.5 + 7.5 ≥ −12.5 + 7.5

t ≥ −5

The afternoon temperature could have been –5°F or warmer.

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.