she saved $3, and we know the discount is 15%, so her savings is that 15%, thus we know 15% of that purchase is 3.
let's say the full price is x, and therefore the 100%, if we know 3 is the 15%, what is x?

Slope intercept: y = mx + b
Y = 5x + b
10 = -20 + b, b = 30
Equation: y = 5x + 30
So, you have to have your equation in terms of dimes. What you said about what he has: four more nickels than dimes in his pocket. Will help with our equation.
We know what a nickel and dime is worth. A nickel is .05 and a dime is .1
We don't know how many dimes are in his pocket, since we're trying to solve it.
.1x+(4+x).05=1.25;
In the parenthesis, it shows how there are four more nickels. Let's solve it now.
.1x + (4+x).05=1.25
.1x + .2+ .05x = 1.25; Let's add like terms.
.15x + .2 = 1.25; Subtract .2 from both sides.
.15x= 1.05
1.05÷.15= 7 =x
There are 7 dimes in his pocket, let's check our answer.
We now know there are 11 nickels, since there are four more nickels than dimes.
11(.05) +.1(7) = 1.25
.55+ .7 = 1.25
Now that we've tried it, we know there are 7 dimes in his pocket.
Tell me if this helps!
Your question seem to me non-understandable. Are they adding up together ?
or multiplying ?
Hello,
2x+y=1
3x-y=-6
==>5x=-5
==>x=-1 and y=1-2*(-1)=3
Sol={(-1,3)}
Answer A