Afood truck sells salads for $6.50 each and drinks for $2.00 each. the food truck’s revenue from selling a total of 209 salads and drinks in one day was $836.50. how many salads were sold that day?

Ans: 93

Explanation: 
The following information is given in the question:
1) Total of 209 salads and drinks.
2) salads for $6.50 each and drinks for $2.00 each; and total revenue was $836.50 

Now let us assign variables to the following entities:
1) Salad = S
2) Drinks = D

From the information given above,
1. S + D = 209 (total number of salads and drinks) -- (A)
2. 6.50S + 2.0D = 836.50 (total revenue equation) -- (B)

From equation (A):
D = 209 - S

Substitute the above equation in (B)
(B) => 6.5S + 2(209 - S) = 836.5
=> 6.5S + 418 - 2S = 836.5
=> 4.5S = 418.5
=> S = 93

Ans: Salads sold that day = 93.

-i

Yes it can cause that

Frequency is the number of complete oscillations of a wave per second.