Answer:
10 cm.
Step-by-step explanation:
[tex]area = lw \\ = (30cm)(20cm) \\ = 600 {cm}^{2} [/tex]
that's the area of the original rectangle. Now add two strips with the same size which results to doubling the original area. ( I used x for the unknown value of the widht)
[tex]2a = lw + 2(lx) \\ 600 {cm}^{2} + 600 {cm}^{2} = (30cm)(20cm) + 2(30x \: \: \: cm) \\ 1200 {cm}^{2} = 600 {cm}^{2} + (60x \: \: \: {cm}^{2})\\ 1200 {cm}^{2} - 600 {cm}^{2} = 60x \: \: \: {cm}^{2} \\ 600 {cm}^{2} = 60x \: \: \: {cm}^{2} \\ \frac{600 {cm}^{2} }{60} = \frac{60x \: \: \: {cm}^{2} }{60} \\ 10 {cm}^{2} = x \: \: \: {cm}^{2} \\ \sqrt{10 {cm}^{2} } = \sqrt{x \: \: \: {cm}^{2} } \\ 10cm = x \: \: \: cm[/tex]
compute and simplify and you will get 10
pa brainliest po!!
