The angles of a triangles are x°, 3x° and 30°. When asked to solve for x, Alvi shows the work in post-it A below. Brian shows the work in post-it B below. Who is correct and why? Why mistake did the incorrect person make? that is the pic for post it a.
the post it b said

x + 3x + 30 = 180
4x + 30 = 180
4x = 150
x = 37.5

See explanation

Step-by-step explanation:

OK.  Alvi is incorrect because he didn't add the measures of all 3 angles of the triangle, whereas Brian did.  So, Brian is correct and Alvi needs to work on that kind of problem.

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