9514 1404 393
Answer:
(x, y) = (3.5, -4)
Step-by-step explanation:
Elimination is easiest if one of the coefficients of a variable is a multiple of the other coefficient of the variable. Here, we have x-coefficients of 4 and 8, so it will be easiest to eliminate x.
Subtract the second equation from 2 times the first.
2(4x +7y) -(8x +5y) = 2(-14) -(8)
9y = -36 . . . . . simplify
y = -4 . . . . . . . divide by 9
4x +7(-4) = -14 . . . . substitute for y in the first equation
4x = 14 . . . . . . . add 28
x = 3.5 . . . . divide by 4
The solution is (x, y) = (3.5, -4).
Answer:
a)=251.2 cm b)=50240 cm
Step-by-step explanation:
a) The formula for calculating the circumference of a circle is c=d*pie, where D is the diameter of the circle.
Therefore, C = 2 * 40 * 3.14 = 251.2 cm
b) The distance covered by 200 revolutions of the wheel is 200 times the circumference, 200*251.2=50240 cm.So to think about this we can assume that there is a point A on the wheel, the distance that point A travels when it rotates 200 times.
Answer:
69 years
Step-by-step explanation:
Given that:
Let year of birth = x
This year = 2020
Year of 25th birthday = x + 25
Year of 55th birthday = x + 55
Present age = 2020 - x
Hence,
x + 2020 - (x + 25 + x + 55) + (2020 - x) = 58
x + 2020 - (2x + 80) + (2020 - x) = 58
x + 2020 - 2x - 80 + 2020 - x = 58
-2x + 4040 - 80 = 58
-2x + 3960 = 58
-2x = 58 - 3960
-2x = - 3902
x = 1951
Birth year = 1951
,
Hence, age =
2020 - 1951 = 69 years
