How do you simplify #2 - 5(3t - 4)#?

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Answer 1 · 2015-11-19T15:05:58

#22-15t#

the 5 multiplies everything inside the brackets so you have:

#2 - ( 5 times 3t - 5 times 4)#

#2 - ( 15t -20)#

But that is not the end of it! You have a minus in front of the bracket.
This is the same as multiplying everything inside the brackets by (-1).

By the way, another way of looking at ' plus ' is as 'put with'; and at subtract as 'remove from':

Now we have :

#2 -1(15t-20)#

Just think about the #-1(15t-20)# on its own for now

We have:

#(-1 times 15t) - (-1 times 20)#

#(-15t)-(-20)#

Negative times negative give you a positive so we have
#-15t + 20#

so #2 - ( 15t -20)# becomes #color(white)(xx)2-15t+20#

regrouping gives

#-15t +2+20#

#-15t+22# which is the same as #22-15t#