algebra help please and thankyoou

Question

Mario recieved y text messages each minute for 10 minutes yesterday and recived t text messages each minute for 20 minutes today what is the total number of text messages he recieved for two days in terms of y and t ?

A )30yt

B) 200yt

C) 20y+10t

D) 10y+20t

Answer 1

Unfortunately, many books, teachers and tutors SKIP OVER the importance of UNITS [maybe, because they are so familiar with these problems that they forget that students aren't so familiar with them].

Use "/" [that is, divide] for "PER" ... like miles/hour for "miles per hour"

[ number of messages ] = [ [ number of messages ] / [minute] ] * [number of minutes]

For yesterday:

[ y messages/minute ] * [ 10 minutes ]

10y messages ... ... ... ... [NOTE: minutes cancel out]

For today:

[ t messages/minute ] * [ 20 minutes ]

20t messages

"total number of text messages he recieved for two days"

Total = [messages received yesterday] + [messages received today]

Total = 10y + 20t

Answer 2

If the problem had, instead, said "Mario received 6 messages each minute for 10 minutes yesterday, the easy result would be 6X10 = 60. Likewise, if it had said 5 messages each minute for 20 minutes today, the easy answer would be 5x20 = 100. Algebra allows us to generalize this to any number of messages: x for yesterday and y for today. But the arithmetic is the same: "y" instead of 6 (or 10 or ANY number), and "x" instead of 5 (or 20 or ANY number). Thus the correct answer is D).

Answer 3

The y goes with the 10 and the t goes with the 20, so the answer is (D), 10y+20t