Every evening Jenna empies her pockets and puts her change in a jar. At the end of the week she counts her money. One week she had 40 coins, all of them dimes and quarters. When she added them up, she had a total of $7.75.
d= number of dimes
q= number of quarters
How many quarters did Jenna have?

Question

Every evening Jenna empies her pockets and puts her change in a jar. At the end of the week she counts her money. One week she had 40 coins, all of them dimes and quarters. When she added them up, she had a total of $7.75.
d= number of dimes
q= number of quarters
How many quarters did Jenna have?

anonymous · Answer

d+q=40 but I don't know what to do next

anonymous · Answer

$$( d + q = 40, 10 d + 25 q = 775 )$$

anonymous · Answer

The second equation concerns pennies.
{ d -> 15, q -> 25 }

anonymous · Answer

ok so then you can substitute the values and find the answer

anonymous · Answer

so 15+25=40

anonymous · Answer

I got 15 dimes and 25 quarters

anonymous · Answer

Replace d below with 40-q
10 d + 25 q = 775 /. d -> 40 - q
solve the following for q:
10 (40 - q) + 25 q = 775

anonymous · Answer

15*10+25*25=775

anonymous · Answer

thank u :D