Question 761259
7 sqrt 245 + 8 sqrt 80 - 3 sqrt 180.

The expression is:

{{{7*sqrt(245) + 8*sqrt(80) - 3*sqrt(180)}}}

= 

{{{7*sqrt(49*5) + 8*sqrt(16*5) - 3*sqrt(36*5)}}}

=

{{{7*(sqrt(49)*sqrt(5)) + 8*(sqrt(16)*sqrt(5)) - 3*(sqrt(36)*sqrt(5))}}}

=

{{{7*7*sqrt(5) + 8*4*sqrt(5) - 3*6*sqrt(5)}}}

=

{{{49*sqrt(5) + 32*sqrt(5) - 18*sqrt(5)}}}

=

{{{63*sqrt(5)}}}

You are right:)