Ajar contains $14.25 in quarters and dimes. there are 75 coins in the jar. find the number of quarters in the jar.
can someone solve this only using 1 variable

X - number of quarters
y - number of dimes

x + y = 75
Dime = 1/10 dollar
Quarter = 1/4 dollar

x×1/4 + y×1/10 = 14.25
y = 75 - x
x×1/4 + (75-x)×1/10 = 14.25
Multiply both sides by 20:
5x + 2×(75-x) = 285
5x + 150 - 2x = 285
3x = 285 - 150
3x = 135
x = 135/3
x = 45