SAT Subject Test Mathematics Level 1

6 . C

This    might   look    at  first   glance  like    a   candidate   for cross   multiplication,

but that    would   just    make    things  more    complicated.    Notice  that    the

fractions   on  both    sides   have    the same    numerator,  19. So  the numerator

is  irrelevant. If  the two fractions   are equal   and they    have    the same

numerator,  then    they    must    have    the same    denominator.    So  just    write   an

equation    that    says    that    one denominator is  equal   to  the other

denominator:

7 . C
Watch what happens when you express everything as powers of 3:

The left    side    of  the equation    is  the product of  powers  with    the same    base,

so  just    add the exponents:

Now the two sides   of  the equation    are powers  with    the same    base,   so  you

can just    set the exponents   equal: