A moving sidewalk at an airport glides a rate of 1.8 feet per second. Walking on the moving sidewalk, you travel 100 feet forward in the same time it takes to travel 40 feet in the opposite direction. Find your walking speed on a nonmoving sidewalk.

The walking speed is 4.2 feet per second.

Step-by-step explanation:

If your walking speed is S, then we can use the relation:

Time = distance/speed.

in the moving sidewalk the speed is S + 1.8ft/s.

moving forward:

speed = S + 1.8ft/s

Distance = 100 feet

Time = T

T = 100ft/(S + 1.8ft/s)

moving in the opposite direction (now the velocity of the moving sidewalk must be subtracted)

speed = S - 1.8ft/s

distance = 40 feet

time = T

T = 40ft/(S - 1.8ft/s)

Then we have two equations:

T = 100ft/(S + 1.8ft/s)

T = 40ft/(S - 1.8ft/s)

We can replace T in the second equation by the expression in the first one:

100ft/(S + 1.8ft/s) =  40ft/(S - 1.8ft/s)

now we can solve it for S.

100ft*(S - 1.8ft/s) = 40ft*(S + 1.8ft/s)

100ft*S - (100ft*1.8ft/s) = 40ft*S + (40ft*1.8ft/s)

100ft*S - 40ft*S = (100ft*1.8ft/s)+ (40ft*1.8ft/s)

S*(100ft - 40ft) = S*60ft = (100ft*1.8ft/s)+ (40ft*1.8ft/s)

S = ( (100ft*1.8ft/s)+ (40ft*1.8ft/s) )/60ft = (252ft^2/s)/60ft = 4.2 ft/s

The walking speed is 4.2 feet per second.

3.4 pizzas

step-by-step explanation:

given is a scatter plot showing number of pizzas sold during weeks for different issues of coupon

y represents number of pizzas sold and x number of coupons issued

y is marked verticaly and x horizontally

the trend line is given as

y =3.4x+43

this says that even when no coupon is issued pizzas sold will be 43

and rate of change of pizza sold for 1 unit of coupon = slope = 3.4

i.e. when x increases by 1 unit y increases by 3.4 units

hence for each additional coupon issued 3.4 pizzas more will be sold