Well first you do 7+5 to equal 12, and then you multiply 12 by 6 and get 72, then you add the 3 to get 75. 6(7+5)+3=75. Hope this helps!!
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.
4280 because 75+5+4200= 4280
