I earn 770.98(R) every week. I have 385.49(R) since I spent the other half on toys. I want extra items on a game, but it's 1,541.72(R). How long will I have to wait until I save enough money for it? 385.49 + 770.98 < 1,541.72. (It's in Russian dollar so lemme translate) 385.49 = 5 US dollar) 770.98 = 10 US dollar) 1,541.72 = 20 US dollar)

1.5 weeks

Step-by-step explanation:

Given

weekly

Required

Determine the time taken to save up

Represent the time with t

The relationship between the given parameters can be expressed as:

Amount + Earnings in t weeks = Game Cost

This gives:

Collect Like Terms

Solve for t

Approximated

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

b because it contains 40% of the possible results from the random list.  

0,1,2,3 v 4,5,6,7,8,9  

4 integers to 6 integers  

40% success vs 60% fail

step-by-step explanation: