7+14+21+28+...+105=1*7+2*7+3*7+4*7+...+15*7
15
∑7*n=7*1+7*2+7*3+7*4+...+15*7=7+14+21+28+...+105
n=1
<span>The object's speed is 8/5 miles per hour or 1.6 mph.</span>
C is 666666688888 from my lookings. Jk
Answer: X = y - yi - 7i
Y = (x + 7i)/(1 - i)
Step-by-step explanation: for the case of (X) you only need to pass the 7i to the other side with the subtraction sign (-7i), then we get this equation:
x + 7i = y − yi
X = y - yi - 7i
in the case of the (Y), first we select the common multiple.
y - yi = y(1 - i)
if we replace it in the original expression, we get the following equation:
x + 7i = y(1 - i)
after that you can pass the value (1 - i) to the other side dividing,
Y = (x + 7i)/(1 - i)
Remark
A cube has six sides, all of them equal. The formula for 1 side is s^2. The formula for all six = 6s^2.
Step One
Find the surface area of the larger cube.
Area = 6 *s^2
s = 15
Area = 6 *15^2
Area = 6 * 225
Area = 1350
Step Two
Find the area of the smaller cube
Area = 6s^2
Area = 6 * 12^2
Area = 6 * 144
Area = 864
Step Three
Find the difference
Area1 - Area2 = difference
1350 - 864 = 486
The difference is area = 486 units^2 <<<<< Answer
There is a slightly shorter way. Take out the common factor of 6
Difference = 6 * (15^2 - 12^2)
Difference = 6 * (225 - 144)
Difference = 6 * (81)
Difference = 486
