Question #b3ab8
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"Find the sum of the integers between 2 and 100 which are divisible by 3 ?"
Let the number be #x#
#$645.40=72%xx x#
#72%xx x=$645.40#
#1%xx x=$645.40-:72#
#~~$8.963888...#
#100%xx x=$8.963888...xx100#
#=896.3888...#
#~~896.4#
# x = $896 7/18# as an exact value
#x=$896.39# as an approximate value
The sign or symbol of % is like a unit of measurement but one that is worth #1/100#
So #1/100# and % are interchangeable.
The word 'of' is a bit like counting. 2 of apples #->2xx"apples"#
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Let the unknown value of dollars be #x#
So #72%" of "x# is the same as #72%xx x#
Then we have #72/100xx x =$645.40#
Multiply both sides by #100/72# (turns the #72/100# on the left into 1)
#72/100xx100/72xx x =100/72xx$645.40#
#72/72xx100/100xx x =100/72xx$645.40#
#1xx1xx x = $896 7/18# as an exact value
#x=$896.39# as an approximate value
