7. to qualify for a lifeguard training course, you have to swim continuously for 500 yards using either the front
crawl or the breast stroke. you swim the front crawl at a rate of 45 yards per minute and the breaststroke at a
rate of 35 yards per minute. you take 12 minutes to swim 500 yards. how much time did you spend swimming
the front crawl?
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Step-by-step explanation:

Front Crawl DATA:

distance = x yrds. ; rate = 45 yrd/min ; time = d/r = x/45 minutes

Breastroke DATA:

distance = 500-x yrds; rate = 35 yrs/min ; time = d/r = (500-x)/3 minutes

EQUATION

tiime + time = 12 minutes:

x/45 + (500-x)/35 = 12

35x + 45(500-x) = 35*45*12

-10x + 45*500 = 35*45*12

-10x = -3600

x = 360 yds. (front crawl distance)

Front crawl time = 360 yds / (45 yds/mim) = 8 minutes

answer: 7

step-by-step explanation: