Mr jones has 20,000 to invest. he invests part at 6% and part at 7%, if hr earns 1,280 in interest after 1 year, how much did he invest at each rate.

Let x be the amount he invests at 6%

1280 = 0.06x + 0.07(20000 - x)
1280 = 0.06x + 1400 - 0.07x
1280 - 1400 = -0.01x
-120 / -0.01 = x
x = 12000

Therefore, he invests $12,000 at 6% and $8,000 at 7%

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.

37/3

step-by-step explanation:

step 1: simplify both sides of the equation.

7x+8(x+

1

4

)=3(6x−9)−8

7x+(8)(x)+(8)(

1

4

)=(3)(6x)+(3)(−9)+−8(distribute)

7x+8x+2=18x+−27+−8

(7x+8x)+(2)=(18x)+(−27+−8)(combine like terms)

15x+2=18x+−35

15x+2=18x−35

tep 2: subtract 18x from both sides.

15x+2−18x=18x−35−18x

−3x+2=−35

step 3: subtract 2 from both sides.

−3x+2−2=−35−2

−3x=−37

step 4: divide both sides by -3.

−3x

−3

=

−37

−3

x=

37

3