1)First, understand that whatever your equation is it’s always gonna be less than 100, because she doesn’t wanna get more than 100 ft.
*>100
2) remember that Lainey already dropped 20 feet. The amount of minutes is your unknown variable (x)
3) so, note that the rate is 20 ft/minute. If you multiply 20 by the amount of minutes she has to descend (your unknown variable: x) you cancel out the “minutes” in the 20 ft/minute fraction.
(Ex. 20ft/min *multiply* x [unknown]minutes= 20ftx)
This is what you want since you need all of the terms to be the same unit to solve with algebra.
4) so, to put it all together you have, 20 times x (representing the unknown amount of minutes) plus 20 (representing the amount she has already fallen) is greater than 100
* 20x+20>100