Q1) Without use of Calculator
The temperature at the bottom of a mountain was 8°C.
The temperature at the top was -26°C.
Find (a) the difference between the two temperatures,
(b) the mean of the two temperatures.

The difference in temperature is 34 degree Celsius while the mean is -17 degree Celsius.

Explanation:

The temperature at the bottom of the mountain is 8 degrees in the positive while the temperature at the top of the mountain is in the negative at -26 degrees.

In the positive and negative scale the way to add and subtract is to simply put the negative number in the bracket and follow the established rules of arithmetic.

Thus to find the difference we see:

8 - (-26)

which is 8 +26 = 34.

The mean of the two numbers is found by simply dividing the resulting difference by 2 and retaining the sign of the numerically bigger number which is -26 so the sign is retained

the mean is -17 degree Celsius.

x=4, y=4

step-by-step explanation:

y=2x-4;

x+2y=12

we can use substitution since the first equation is solved for y

where ever you see y in the second equation, replace it with 2x-4

x + 2(2x-4) = 12

distribute the 2

x+4x-8 = 12

combine like terms

5x-8=12

add 8 to each side

5x-8+8=12+8

5x=20

divide by 5

5x/5 = 20/5

x =4

we still need to solve for y

y = 2x-4

we know x =4

y = 2(4) -4

y = 8-4

y=4