How do you solve #3.25 = a/2.5#?

1 Answer
Apr 24, 2017

Answer:

A slightly different way of thinking about the multiplication

Explanation:

#color(red)("Step 1")#

Write as #" "3.25=1/2.5xxa#

Multiply both sides by #2.5#

#3.25xx2.5=2.5/2.5xxa#

But #2.5/25=1# so the right hand side ends up as just #a#

#3.25xx2.5=a#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(red)("Step 2")#

Write #2.5# as #" "color(green)(2)color(blue)( + 1/2)#

#3.25xx2.5" "->" "color(brown)(3.25)(color(green)(2)" "+" "color(blue)(1/2))" "=a#

#" "6.5" "+" "1.5+0.125=a#

Note that:
#" "color(brown)(3.25)color(green)(xx2) =color(magenta)(6.5)#

#" "color(brown)(3.25color(blue)(xx1/2)->(3+0.25)color(blue)(1/2))->color(magenta)(1.5+0.125)#

#a=color(magenta)(6.5+1.5+0.125)=8.125#