10 less than 5 times the value of a number -> 5a - 10
10 times the quantity of 12 more than one-fourth of a number -> 10(12+1/4a)
We have :
5a - 10 = 10(12 + 1/4a)
5a - 10 - [10(12 + 1/4a)] = 0
5a - 10 - (120 + 5/2a) = 0
5a -10 - 120 - 5/2a = 0
Group : (5a-5/2a) - (10 + 120) = 0
5/2a - 130 = 0
5/2a = 130 -> a = 130 : 5/2 = 52
Recheck : 5 x 52 - 10 = 250
10 x (12 + 1/4 x 52) = 10 x (12 + 13) = 10 x 25 = 250