Seven gallons of a sugar solution was mixed with 4 gallons of a 80 percent sugar solution to make an 72 percent sugar solution. Find the percent concentration of the first solution. (a) 70% (b) 61% (c) 69% (d) 67%

67%

Step-by-step explanation:

Let the percentage of the first solution = x

7 gallons + 4 gallons = 11 gallons

Our system of equation is

Seven gallons of a sugar solution was mixed with 4 gallons of a 80 percent sugar solution to make an 72 percent sugar solution.

7 gallons × x % + 4 gallons × 80% = 72% × 11 gallons

= 7x + 3.2 = 7.92

Collect like terms

7x = 7.92 - 3.2

7x = 4.72

x = 4.72/7

x = 0.6742857143

Converting to percentage

0.6742857143 × 100

= 67.42857143%

Approximately, the percent concentration of the first solution is 67%

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°