Can i pls have help with is so confused

500.

Solution:  210 is 42% of X  

Equation: Y = P% * X  

Solving our equation for X

X = Y/P%

X = 210/42%  

Converting percent to decimal:

p = 42%/100 = 0.42  

X = 210/0.42  

X = 500

x = 3 ± √(5+y)

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places