What is the justification for the step taken from line 2 to line 3?

5 lines of math. the first line has, 3 x plus 9 minus 7 x equals x plus 10 plus x. the second line has, negative 4 x plus 9 equals 2 x plus 10. an arrow pointing from the front of the second line to the front of the third line. the third line has, negative 6 x plus 9 equals 10. the fourth line has, negative 6 x equals 1. the last line has x equals negative startfraction 1 over 6 endfraction.

the subtraction property of equality
the multiplication property of equality
combining like terms on one side of the equation
the distributive property

Martin likes to make flower bouquets that have 3 daffodils and 4 tulips per vase. a daffodil has a mass of d grams, a tulip has a mass of t grams, and the vase has a mass of u grams. the expression 5(3d + 4t + v) describes the mass of 5 bouquets. match each amount in the situation with the expression that represents it. situation expression number of bouquets mass of one bouquet mass of the tulips in one bouquet 4t mass of the daffodils in one bouquet 3d + 4t + v

What is the value of x when x + 7 = 21?

Someone answer asap for ! a discount store’s prices are 25% lower than department store prices. the function c(x) = 0.75x can be used to determine the cost c, in dollars, of an item, where x is the department store price, in dollars. if the item has not sold in one month, the discount store takes an additional 20% off the discounted price and an additional $5 off the total purchase. the function d(y) = 0.80y - 5 can be used to find d, the cost, in dollars, of an item that has not been sold for a month, where y is the discount store price, in dollars. create a function d(c(x)) that represents the final price of an item when a costumer buys an item that has been in the discount store for a month. d(c(x)) =