That is going to be 48 for the first question because 6x8 equals 48
10x-(3x7-3x2x)+18
10x-(21-3x2x)+18
10x-(21-6x)+18
10x-21+6x+18
16x-21+18
16x-3
Call the price of the bike before mark up 'x', then we have:
x + 0.25x = 210
1.25x = 210
x = 168
Therefore, the bike cost $168 before 25% price increase.
