30 since that’s the lowest number both 3 and 10 can fit in
The answer would be the third option or C
90/ [10(3^2 - 4)]
= 90/ [ 10 (5)]
= 90/ 50
= 9/5
= 1.8
Get everything on one side:

. Now we can factor to find the solutions. What we ask ourselves here is "What 2 numbers will add to be +4 and multiply to be -21?" +7 and -3 work because 7-3 = 4 and 7 * -3 = -21. So our factors are (x+7)(x-3). Our solutions, however, are found using the Zero Product Property. If x + 7 = 0, then x = -7. If x - 3 = 0, then x = 3. So our solutions are x = -7 and x = 3.