[tex]a) \frac{70}{100} \times x = 98[/tex]
[tex] \frac{70x}{100} = 98[/tex]
[tex] \frac{7x}{10} = 98[/tex]
[tex]7x = 980[/tex]
[tex]x = \frac{980}{7} [/tex]
[tex]x = 140[/tex]
[tex]b) \frac{21}{100} \times x = 51[/tex]
[tex] \frac{21x}{100} = 51[/tex]
[tex]21x = 5100[/tex]
[tex]x = \frac{5100}{21} [/tex]
[tex]x = \frac{1700}{7} [/tex]
[tex]x = 242.85[/tex]