Answer:
The height of the football after 4 seconds is 80 feet.
Step-by-step explanation:
You know that the height (in feet) of punted football is a function of the time the ball is in the air and it is defined by:
h(t) = -7*t²+48*t
To calculate the height of the ball after 4 seconds, you must replace the time t by the time of 4 seconds:
h(4) = -7*4²+48*4
Solving, you get:
h(4) = -7*16+48*4
h(4) = -112+192
h(4)= 80
<u><em>The height of the football after 4 seconds is 80 feet.</em></u>
Use the equation .8x + x = 252
x is the number, and .8 is the decimal equivalent of 80%.
1.8x = 252
x = 140
Check the picture below, let's use those two points on the line to get its slope.

Answer:
12 square cm correct to 2 significant figures
Step-by-step explanation:
Area of a Rectangle = L X B = 2.1 X 5.6 = 11.76 square cm
To round your result to 2 significant figure, we start counting from the left from the first non-zero digit.
The first two digits are 11 but because the number after is 7 (greater than 4), we round up to 12.
11.76 square cm = 12 square cm correct to 2 significant figures