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# help

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A store sells the basic model of a phone for \$60 and the upgraded model for \$200. It costs the store \$10 to buy each basic model
and \$50 to buy each upgraded model from the phone company. On Tuesday, the store has \$1,800 in sales for these two models,
and it paid the phone company \$400 to buy these phones. How many upgraded models did the store sell on Tuesday?

Feb 12, 2020

#1
+1

Let  x  =  number of basic models.

Let  y  =  number of upgraded models.

Sales:      60x + 200 y  =  1800                                          60x + 200y  =  1800

Purchase:  10x + 50y  =  400               --->   x -4   --->     -40x  - 200y  =  -1600

Adding down the columns:                                                 20x             =  200

x  =  10     <---  number of basic models

Substituting:  10x + 50y  =  400     --->     10(10) + 50y  =  400     --->     100 + 50y  =  400

--->     50y  =  300     --->     y  =  6     <---   number of upgraded models

Feb 12, 2020

#1
+1

Let  x  =  number of basic models.

Let  y  =  number of upgraded models.

Sales:      60x + 200 y  =  1800                                          60x + 200y  =  1800

Purchase:  10x + 50y  =  400               --->   x -4   --->     -40x  - 200y  =  -1600

Adding down the columns:                                                 20x             =  200

x  =  10     <---  number of basic models

Substituting:  10x + 50y  =  400     --->     10(10) + 50y  =  400     --->     100 + 50y  =  400

--->     50y  =  300     --->     y  =  6     <---   number of upgraded models

geno3141 Feb 12, 2020