A jar contains 5-gram bolts and 10-gram bolts. the contents of the jar weigh 3.8 kg. if there are 460 bolts, how many 10-gram bolts are there in the jar? (convert kg to grams.)

Respuesta :

The number of 10 gram bolts in the jar is 300.

Explanation

Lets assume, the number of 5 gram bolts is [tex]x[/tex] and the number of 10 gram bolts is [tex]y[/tex]

Total weight of all bolts = 3.8 kg = (3.8 × 1000) grams = 3800 grams

So, the first equation will be:  [tex]5x+10y= 3800 .........................( 1 )[/tex]

Now the total number of bolts is given as 460. So, the second equation will  be :   [tex]x+y=460 ............................(2)[/tex]

Solving equation (2) for y itself, we will get....

[tex]y= 460-x[/tex]

Now, substituting this [tex]y= 460-x[/tex] into equation (1) in place of [tex]y[/tex].....

[tex]5x+10(460-x)= 3800\\ \\ 5x+4600-10x=3800\\ \\ -5x+4600=3800\\ \\ -5x= 3800-4600\\ \\ -5x= -800\\ \\ x= \frac{-800}{-5}=160[/tex]

Plugging this [tex]x= 160[/tex] into the equation [tex]y= 460-x[/tex] , we will get...

[tex]y= 460-160=300[/tex]

So, the number of 10 gram bolts in the jar is 300.