Let d = number of dimes, q = number of quarters
<span>Sally has 20 coins in her piggy bank, so </span>
<span>d + q = 20 </span>
<span>The total amount of money is $3.05. </span>
<span>Use the value of each coin multiplied by its number to get total value </span>
<span>.10d + .25q = 3.05 </span>
<span>multiply everything by 100 to clear the decimal places </span>
<span>10d + 25q = 305 and </span>
<span>d + q = 20 </span>
<span>solve the second equation above in terms of either d or q - lets do d </span>
<span>d = 20 - q </span>
<span>sub that into the first equation </span>
<span>10d + 25q = 305 </span>
<span>10(20 - q) + 25q = 305 </span>
<span>200 - 10q + 25q = 305 </span>
<span>15q = 105 </span>
<span>q = 105/15 = 7 </span>
<span>and from above </span>
<span>d = 20 - q = 20 - 7 = 13 </span>
<span>so, there are 13 dimes and 7 quarters </span>
<span>verify with orig problem </span>
<span>13 + 7 = 20, OK, and $1.30 + $1.75 = $3.05
</span>
3(x-7)+8=-20
Multiply the bracket by 3
(3)(x)(3(-7)+8= -20
3x-21+8= -20
3x-13= -20
Move -13 to the other side. Sign changes from -13 to +13.
3x-13+13= -20+13
3x= -7
Divide by 3
3x/3= -7/3
x= -7/3 or in mixed number : -2 1/3
Answer : x= -7/3 or in mixed number : -2 1/3
First thing to do is to solve each of these for y. The first one is y=-4x-3; the second one is y=4x-21; the third one is y=4x+21; the fourth one is y=-4x+3. From that you can tell the positive slopes are found in the second and third equations. Those are the ones we will test now for the point (3, -9). y=-9 and x=3, so let's fill in accordingly. The second equation filled in is -9=4(3)-21. Does the left side equal the right when we do the math? -9=12-21 and -9=-9. So the second one works. Just for the sake of completion, let's do the same with the third: -9=4(3)+21. Does -9=12+21? Of course it doesn't. Our equation is the second one above, y+9=4(x-3).
Answer:
y = -(3/7)x + 2
Step-by-step explanation:
(see attached)
recall that the slope-intercept form of a linear equation is
y = mx + b
where m = slope = given as -(3/7)
and b = y-intercept = 2
substituting these values into the eqation:
y = mx + b
y = -(3/7)x + 2
I have a photo that shows how I got the answer and what the answer is (Key: Red represents my work, while highlighter shows what the answer is):
