Question 201879: 1. A disc jockey must play 16 commercial sports during 1 hour of a radio show. Each commercial is either 30 seconds or 60 seconds long. If the total commercial time during 1 hour is 13 min, how many 30-second commercial were played that hour? How many 60-second commercials?
2.The Everton College store paid $1834 for an order of 50 calculators. The store paid $ 10 each scientific calculator. The others, all graphing calculators, cost the store $56 each. How many of each type of calculator was ordered?
3.Snookers Lumber can convert logs into either lumber or plywood. In a given day, the mill turns out three times as many units of plywood as lumber. it makes a profit of $30 on a unit of lumber and $45 on a unit of plywood. How many of each unit must produced and sold in the order to make a profit of $16830?
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Answer by scott8148(6628)   (Show Source):
You can put this solution on YOUR website! 1. let t="30 sec commercials" and s="60 sec commercials"
"A disc jockey must play 16 commercial sports during 1 hour" ___ t + s = 16 ___ t = 16 - s
"total commercial time during 1 hour is 13 min" ___ 60t + 30s = 13 * 60
substituting ___ 60 (16 - s) + 30s = 13 * 60
960 - 60s + 30s = 780 ___ -30s = -180 ___ s = 6
substituting ___ t + 6 = 16 ___ t = 10
follow this same technique for the other questions
2. let s="scientific calcs" and g="graphing calcs"
"an order of 50 calculators" ___ s + g = 50 ___ s = 50 - g
"The Everton College store paid $1834"
" The store paid $ 10 each scientific calculator. The others, all graphing calculators, cost the store $56 each" ___ 10s + 56g = 1834
substituting ___ 10 (50 - g) + 56g = 1834
solve for g, and then substitute to find s
3. let L="lumber units" and p="plywood units"
"three times as many units of plywood as lumber" ___ p = 3L
"it makes a profit of $30 on a unit of lumber and $45 on a unit of plywood. How many of each unit must produced and sold in the order to make a profit of $16830"
30L + 45p = 16830
substituting ___ 30L + 45 (3L) = 16830
solve for L, and substitute to find p
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