SOLUTION: Bill and Mark have a combined mass of 85kg. Marks mass is 20kg less than twice Bills mass. What is each boys mass. Write equation. Write bills mass. Write marks mass

Algebra ->  Test -> SOLUTION: Bill and Mark have a combined mass of 85kg. Marks mass is 20kg less than twice Bills mass. What is each boys mass. Write equation. Write bills mass. Write marks mass      Log On


   

Question 786564: Bill and Mark have a combined mass of 85kg. Marks mass is 20kg less than twice Bills mass. What is each boys mass. Write equation. Write bills mass. Write marks mass
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +b+%2B+m+=+85+
(2) +m+=+b+-+20+
Substitute (2) into (1)
(1) +b+%2B+%28+b+-+20+%29+=+85+
(1) +2b+-+20+=+85+
(1) +2b+=+105+
(1) +b+=+52.5+
and, since
(2) +m+=+b+-+20+
(2) +m+=+52.5+-+20+
(2) +m+=+32.5+
Bill weighs 52.5 kg
Mark weighs 32.5 kg
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check:
(1) +b+%2B+m+=+85+
(1) +52.5+%2B+32.5+=+85+
(1) +85+=+85+
OK