How many minutes and hours are in 175, 336, and 750?

I'm assuming its 175, 336 and 750 minutes? 

175 minutes: 
175 divided by 60
= 2 remainder 55
= 2 hours and 55 minutes 

336 minutes: 
336 divided by 60 
= 5 remainder 36 
= 5 hours and 36 minutes 

750 minutes: 
750 divided by 60 
= 12 remainder 30
= 12 hours and 30 minutes 

Ok here's your system:

n+d=160
0.05n+0.10d=10.50

Steps:

I will try to solve your system of equations.

d+n=160;0.1d+0.05n=10.5

Step: Solved+n=160for d:

d+n+−n=160+−n(Add -n to both sides)

d=−n+160

Step: Substitute−n+160fordin0.1d+0.05n=10.5:

0.1d+0.05n=10.5

0.1(−n+160)+0.05n=10.5

−0.05n+16=10.5(Simplify both sides of the equation)

−0.05n+16+−16=10.5+−16(Add -16 to both sides)

−0.05n=−5.5

−0.05n−0.05=−5.5−0.05(Divide both sides by -0.05)

n=110

Step: Substitute110fornind=−n+160:

d=−n+160

d=−110+160

d=50(Simplify both sides of the equation)

d=50 and n=110

so there are 110 nickels