This is the concept of algebra, we are required to find a number,x, such that 87 decreased by three times a number is great than one hundred and sixty-five.
Supposed the number is x, three times the number will be:
3*x=3x
thus;
87-3x≥165
-3x≥165-87
-3x≥78
dividing both sides by -3 we get:
(-3x)/(-3x)≥78/(-3)
x≤-26
This implies that the number is less than or equal to 26