90% of the 50 US States have mountains. How many states have mountains? whats the answer its percents

Ineed with number 6 , explain how to get 1978

Rewrite the following quadratic functions in intercept or factored form. show your work. y = 5x^2 + 10x

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.