ALGEBRA B55

If  1m  =  7; find m

     3

Solution

1m  =  7

3

¹3 x 1m  =  7 x  3     multiply by 6 both sides

      ₁3

1m = 7 x 3

m = 21

Hence m = 21

AREAS A2

Area of triangle is 60mm². If base is 10mm, find height.

Solution

Area =  1 x base x height

             2

Let height = h

60 =  1 x 10  x h

         2

60 =  1 x 10⁵ x h,     canceling by 2

          2₁

60 =  1 x 5  x  h

60 = 5h

            

¹²60 =  ¹5h

   ₁5       ₁5

h = 12mm

hence height is 12mm

TRY THIS…………………

Area of triangle is 70mm². If base is 20mm, find height.

ALGEBRA B54

If 20y = 660; find y

Solution

20y = 660

20y =660          [divide by 20 both sides.]

20       20

y = 33

Hence y = 33

AREAS A1

Find the area of the triangle having base of 15cm and height of 20cm.

Solution

Area =  1 x base x height

             2

             base=15cm, height=20cm.

Area =  1 x 15 x 20

             2

Area =  1 x 15 x 20¹⁰     [canceling by 2]

             2₁

Area =  1 x 15 x 10

            

Area =  150

Hence Area is 150 cm²

TRY THIS……………………..

Area of a rectangle is 90 cm². Find its perimeter if its width is 5cm.

ALGEBRA B53

If 20y = 120; find y.

Solution

20y = 120

20y =120          [divide by 20 both sides.]

20       20

y = 6

Hence y = 6

PERIMETERS A1

Area of a rectangle is 63 cm². Find its perimeter if its width is 7cm.

Solution

First we find length

A = l x w

63 = l x 7

63 = 7l

7       7

9 = l

Now length is 9cm.

We can find perimeter since we have both length and width.

P = 2(l + w)

=2(9 + 7)

=2 x 16

=32

Hence perimeter is 32cm

TRY THIS……………………..

Area of a rectangle is 84 cm². Find its perimeter if its width is 7cm.

ALGEBRA B52

if  1t  =  11; find t

     7

Solution

1t =  11

7

¹7 x 1t  =  11 x  7     multiply by 8 both sides.

      ₁7

1t = 11 x 7

t = 77

Hence t = 77