Check the picture, notice the domain in red.
recall that the domain is the values for the x-coordinate, whilst the range is the values for the y-coordinate.
3x8+4 because 3 times so that is 3 x the sum of 8 and 4 so 8+4 together it would be 3x8+4
Round each coin weight to the nearest gram first, penny 3g, nickel 5g, dime 2g, quarter 6g, half dollar 11g. Now add those numbers together as he has one of each coin 3+5+2+6+11=27 grams
You haven't written the question properly because we have nothing to base y on.