First find the slope of the line given.
Re-write the equation in the slope form of y=mx+ c where m is the slope and c is the y-intercept
2x+ 10y =20
2x-2x+10y=-2x+20
10y= -2x +20
10y/10 = -2x/10 + 20/10
y= - 1/5 x + 2
The slope m1 = -1/5
A line perpendicular to this line will have a slope lets say m2 where ;
m1 * m2 = -1
-1/5 * m2 = -1
-1/5 m2 = -1
5* -1/5 m2 = -1* 5
-1 m2 = -5
-1m2/-1 = -5/-1
m2 = 5
The slope of a line perpendicular to the line with equation 2x+10 y=20 will be 5